The Echo SRM2400 string trimmer has only one area that needs grease: the gearbox at the end of the shaft that converts the power coming from the engine through the gearing to turn the string trimmer head. The speed at which the gears turn generates a high amount of heat. As the lubrication starts to break down, the gears will start to burn and crack. Regular greasing allows the gearbox a long life, and the procedure only takes 10 minutes to complete.
Set the trimmer on a flat workbench. Locate the gearbox at the end of the driveshaft; the string trimmer head is attached to it.
Wipe any debris from the gearbox with the clean rag. Remove the plug from the right side of the gearbox with the crescent wrench.
Squeeze the lithium-based grease into the plug hole until the grease is at the bottom of the threads. Reinstall the plug with the crescent wrench.